The invention generally relates to estimating and using slowness vector attributes in connection with a multi-component seismic gather.
Seismic exploration involves surveying subterranean geological formations for hydrocarbon deposits. A survey typically involves deploying seismic source(s) and seismic sensors at predetermined locations. The sources generate seismic waves which propagate into the geological formations creating pressure changes and vibrations along their way. Changes in elastic properties of the geological formation scatter the seismic waves, changing their direction of propagation and other properties. Part of the energy emitted by the sources reaches the seismic sensors. Some seismic sensors are sensitive to pressure changes (hydrophones), others to particle motion (geophones), and industrial surveys may deploy only one type of sensors or both. In response to the detected waves, the sensors generate electrical signals to produce seismic data. Analysis of the seismic data can then indicate the presence or absence of probable locations of hydrocarbon deposits.
Some surveys are known as “marine” surveys because they are conducted in marine environments. However, “marine” surveys may be conducted not only in saltwater environments, but also in fresh and brackish waters. In a first type of marine survey, called a “towed-array” survey, an array of streamers and sources is towed behind a survey vessel. In a second type of marine survey, an array of seismic cables, each of which includes multiple sensors, is laid on the ocean floor, or sea bottom; and a source is towed behind a survey vessel.
Historically, towed-array seismic surveys only employed pressure waves, and the sensors detected passing pressure wavefronts. The art has recently begun moving to “multi-component” surveys in which the sensors also detect particle velocities.